Production of Diacetyl, 2-Acetolactate and Acetoin by Yeasts During Fermentation

Abstract

Results are given for the production of diacetyl, 2,3-pentandione-l-acetolactate, 2-acetohydroxy butyrate, acetoin and 3-hydroxy-2-pentanone for 13 yeasts belonging to the genus Saccharomyces. The data presented indicate that in general the yeasts do not produce significant amounts of vicinal diketones during unstirred laboratory fermentations. The observed maximum levels of diacetyl ranged from 0*02-0*32 ppm averaging 0-09 ppm (0*07 ppm if S. carlsbergensis (strain H) is omitted). During active fermentation all the yeasts tested produced 2-acetohydroxy acids. The 2-aceto hydroxy acids and the 3-hydroxy-2-ketones are determined gas chromatographically by stepwise conversion of the four compounds to diacetyl and 2,3-pentandione. The maximum amounts of 2-acetolactate produced by the yeasts tested averaged 0*7 ppm, ranging from 0*08-1*65 ppm.

Physiology, ecology and industrial applications of aroma formation in yeast

“…Due to the highly reductive conditions that exist at the end of alcoholic fermentations, the concentration of diacetyl is usually below (or close to) its sensory detection threshold in fresh beer (Haukeli and Lie 1972 ). Diacetyl reduction effectively eliminates the undesired flavors as acetoin and 2,3-butanediol do not contribute to the aroma profile.…”

Origin and Production of Acetoin during Wine Yeast Fermentation

“…Yeasts belonging to the genus Saccharomyces produce ␣-acetolactate in considerable amounts during fermentation, and this highly labile compound may easily be converted to diacetyl or to acetoin, particularly in the presence of oxygen (28). An oxygen-poor medium (0.2 mg of O 2 per liter) leads to the most rapid ␣-acetolactate formation, and maximum levels are obtained in an overaerated medium (17.4 mg of O 2 per liter).…”

Effect of pH, aeration and feeding non-sterilized agave juice in a continuous agave juice fermentation

“…Acetoin and diacetyl, which are important in the final bouquet of alcoholic beverages, were not detected for any of the conditions tested with sterilized agave juice; these results might be explained since S. cerevisiae has generally low acetoin and diacetyl production which commonly occurs at the beginning of batch fermentation 18…”